Which Colon Screening Method is Safest?
Colonoscopy causes more perforations than sigmoidoscopy
Feb. 4, 2003 -- Although the benefits of colorectal cancer
screening far outweigh the risks for most people, new research shows that
sigmoidoscopy procedures may be less likely to cause complications than the
more extensive colonoscopy procedure.
The study, published in the Feb. 5 issue of the Journal of
the National Cancer Institute, found that while the risk of damaging the
colon wall during either procedure is very small, a sigmoidoscopy is only about
half as likely to perforate or damage the colon wall as a colonoscopy.
A colonoscopy is a procedure that uses a small scope equipped
with a camera inserted through the rectum to examine the entire length of the
colon for abnormalities. Sigmoidoscopy uses a similar technique, but the scope
only examines the section of the colon closest to the rectum.
Because it reaches a much smaller area of the colon,
researchers say the less-expensive sigmoidoscopy is expected to have a lower
incidence of perforation, but few studies have backed up that assumption.
In this study, researcher Nicolle M. Gatto, of the Mailman
School of Public Health at Columbia University, and colleagues compared the
risks of perforation of the colon associated with sigmoidoscopy and colonoscopy
among people 65 and over who had undergone at least one of the procedures
between 1991 and 1998.
Researchers found that 77 cases of perforation among the 39,286
colonoscopies studied compared to only 31 such cases among the 35,298
sigmoidoscopies studied. That translates to almost two perforations for every
1,000 colonoscopies performed and nearly one perforation for every 1,000
sigmoidoscopies. Of those who had perforations, the researchers noted that
roughly 5% died within 14 days of the procedure.
Researchers say that the difference in risk between the two
procedures has narrowed in recent years due to improvements in technology and
training among doctors that perform the procedures, which have made both
procedures -- especially colonoscopies -- safer.
Regular colorectal cancer screening is recommended for all
adults once they reach age 50 and even earlier if they have a family history or
other risk factors for the disease. Recent research suggests that colonoscopy
is the most effective colorectal cancer screening method because it's the only
one that looks at the entire colon. But it's also the most expensive and
invasive procedure, which means other methods may be appropriate for some
people or if colonoscopy is unavailable.
In fact, a national task force proposed new colorectal
cancer screening guidelines this week that call for more extensive use
of colonoscopy as the preferred screening method for most people.